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Population Estimation Example for Estuaries
Illustrative Example Objectives:
- Estuarine example for continuous resource, area in sq.km.
- Estimation based on 2 years of sampling data
- Benthic IBI and Water Quality Index
- Target Sampled, Non-Target, and Not Needed Site Status
- Download all files (est_example.zip 34 KB) or individual files
- How to run this Estuaries Example Guide or download estexamguide2.9. (pdf 8 KB)
Another illustrated example has been included based on streams.
Example is based on R 2.2.1 and psurvey.analysis_2.9 (other R versions please see: R Compatability Notice)
Design, Site Evaluation, Weight Adjustment, Estimation, Reported Results
Background: Information for this example is drawn from the South Carolina Estuaries Monitoring program and report, Van Dolah, R.F., et.al. 2002. However, simplifying assumptions regarding the frame materials, design, and site evaluations have been made, therefore, this example material is for illustrative purposes only.
- Target Population includes two sub-populations: Tidal Creeks and Open Water
- GRTS Design: Five year rotating panels, 30 sites/year/population, oversample of 30 sites/year/population (a minor simplification for illustration)
- Sample Frame - GIS coverage supplied by South Carolina, based on NWI maps, Tidal Creek Area = 105.8 sq. km, Open Water Area = 628.5 sq. km (Design information, EPA/WED Corvallis)
- Two years of sample observations (data for several WQ parameters and Benthic IBI obtained from Van Dolah, R.F., et.al. 2002)
- Definitions of good, marginal, and poor values of WQ and Benthic IBI indices from Van Dolah, R.F., et.al. 2002
- The design for this example is a composite of the first panel of the design used for the 1999 sampling and the first four panels of the 2000 design.
- Sample ID numbers were assigned consecutively and panels renumbered from 1 to 4.
- Initial weights were assigned assuming a sample size of 30, Tidal Creek weights = 3.53, Open Water weights = 20.95.
- The est_design includes a total of 600 sites: 30 sample sites + 30 oversample sites = 60 sites/yr for 5 yrs = 300 sites for Tidal Creeks and 300 sites for Open Water ( txt 35 KB)
- Site Status values (Target Sampled, Non-Target, Not Needed) were assigned to all sites in panels 1 and 2 for both Tidal Creeks and Open Water.
- Sites with reported sample observations (Van Dolan, R.F., et.al. 2002) were assigned Target Sampled status and several water quality and biological parameters and indices added to the Site Evaluation File: siteeval (txt 17 KB)
- Sites without reported sample observations, with Site ID's included within the range of sampled sites, were assigned Non-Target Status.
- Sites with Site ID's greater than the range of sampled sites, were assigned Not Needed Status.
- Required: R Statistical Package 2.2.1+ psurvey.analysis_2.9
- R Procedures: adjustwts (txt 3 KB), adjustwtsR (R script 3KB)
- Output: (txt 3 KB) designstatus (cvs 26 KB)
- R console - a documentation file R_History (txt 13 KB))
- Required: R Statistical Package 2.2.1+ psurvey.analysis_2.9
- Input: designstatus
- R Procedures estimation (txt 6 KB), estimationR (R script 6KB)
- Estimates for both Bentic IBI and Water Quality Index
| Description | Estimates |
| Estimates by Indicator Score | scoresumcdf (cvs 7 KB) |
| Estimates at % levels | scoresumpct (cvs 4 KB) |
| Estimate for Total | scoresumtot (cvs 2 KB) |
| Benthic IBI, Water Qualtiy Index | ow_ibiwqsum (cvs 3 KB) |
| CDF plots | results (pdf 22 KB) |
| R console documentation | R_History (txt 13 KB) |
Figure 3.4.5 Percent Habitat Benthic IBI, source: The Condition of South Carolina's Estuarine and Coastal Habitats During 1999-2000, Technical Report, Van Dolah, R.F., et.al. 2002. The data and estimates in this example do NOT match exactly those in the report, due to simplifying assumptions and data changes in this example.
Additional results and graphics for South Carolina Estuaries
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